


Promises

by sos_blimek25



Category: Toaru Kagaku no Railgun | A Certain Scientific Railgun
Genre: F/F, First Kiss, Fluff, Pining, Romance
Language: English
Status: Completed
Published: 2021-01-26
Updated: 2021-01-26
Packaged: 2021-03-12 01:53:57
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,265
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29002527
Author URL: https://archiveofourown.org/users/sos_blimek25/pseuds/sos_blimek25
Summary: Mikoto’s struggling with her sexuality, and Kuroko has a surprisingly simple suggestion.“One way to discover whether you like girls,” Kuroko twirled a finger in the air, “is to kiss one.”
Relationships: Misaka Mikoto/Shirai Kuroko
Comments: 7
Kudos: 75





	Promises

**Author's Note:**

> I've had this MikoKuro one-shot sitting on my computer for months. Got around to re-working it recently, and I'm finally happy with it! It was nice to write these two for a change.
> 
> Let me know what you think!
> 
> For fic updates and Railgun ramblings follow me on [twitter.](https://twitter.com/sos_blimek25) Thanks!

“Kuroko. Can I talk to you about something?”

Mikoto hated asking for help. She could usually fall asleep while her roommate worked at her desk; the pen scratching, the page-turning, the dim lights of the dorm room never bothered her. But tonight, it was impossible.

Every sound rung in her ears. Her jaw was clenched so tightly it hurt. Her body was tense, quivering ever so slightly under her bedsheets, and her skin burning to the touch. There were too many thoughts swimming in her head, pushing her to the brink of anxiety that, for once, she doubted she could face it alone.

And so, she had swallowed her pride and asked for help.

“Of course, Onee-sama.” Kuroko barely looked up from her work before giving a response. She was caring, almost too caring sometimes, and Mikoto wondered what she had done to deserve such a loyal best friend. Perhaps it would be her downfall someday — but in times like these, Mikoto couldn’t be more grateful.

She pulled her legs to her chest. Her heartbeat was rising and rising in her throat, she tried to swallow it back down, but to no avail. It was just Kuroko, sure, but it was still daunting.

Mikoto took a deep breath. “It’s kinda personal, so… don’t be weird about, it okay?” There was a pause, and even without seeing her expression, she knew Kuroko wasn’t quite following. “You’ll know as soon as I say it, just— just promise you won’t freak out, please?”

With a raised eyebrow, Kuroko glanced over her shoulder. She saw Mikoto’s expression — a furrowed brow and a twitching frown, suggesting she was deep in thought. Whatever plagued her was something serious.

Kuroko shut her books and put down her pen. “Well, alright,” she said, standing from the desk. She sat down on the edge of her bed, gazing across at Mikoto, who was all too adorably wrapped up in blankets. “Since it seems to be something of importance, I promise, Onee-sama. But I admit, you’ve made me awfully curious.”

Mikoto could barely look at her, her chest pinched at the slightest hint of eye-contact. Kuroko waited patiently, but it took forever before any words came out. Mikoto pulled the blanket up to her nose, muffling her voice, as she reluctantly spoke.

“I’ve been thinking a lot lately, that’s all,” she said. She felt she was a thousand feet up, crossing a tightrope, and each word a hesitant step forward. The ceiling began to wobble, and she took another slow breath to steady herself. “I-I think I might be, um… you know…”

“Might be?”

And then, nothing. Her airways shut, and Mikoto couldn’t take another breath. Her chest rose in sharp, painful puffs. The words refused to come out as if clawing and tearing to stay inside her throat.

“How did you…” Mikoto sighed, her cheeks flaming hot. “How did you figure out you liked girls? ‘Cause I might too. Maybe. I don’t know.”

That was the last thing Kuroko expected to come out of Mikoto’s mouth. She had dreamt of it many times, but realistically, never thought she’d see the day. Kuroko’s chest was rising, inflated with hope, and her thoughts ran wild, urging her to pounce on Mikoto then and there — but her promise tethered her to her senses.

She couldn’t betray her Onee-sama.

“Don’t— don’t say anything! You promised.” In response to Mikoto’s fiery glare, Kuroko put her hands up in surrender, and her sly grin gave way to a polite smile. She was sweating and her heartbeat was racing, but she had to compose herself. She had to.

“Am I to answer your question?” Kuroko asked.

“O-Oh,” Mikoto blinked. “Yes, please.”

“Everyone’s experiences are different, Onee-sama, I will preface with that,” Kuroko put a hand to her chest. “As you know, you were my first love, and I hadn’t any interest in romance before that. I could never imagine myself intimate with a man — they always appeared so dull to me. But, there was something charming about you that drew me in, something I had never experienced before. It’s a rather anti-climactic story, but it occurred to me one day that I never looked at men the way I looked at women — especially you. Do you understand?”

“Yeah,” Mikoto was awfully attentive. “Yeah, so it just… clicked after a while?”

“I suppose.” Kuroko gave a sympathetic smile. “My apologies, Onee-sama, I know that doesn’t bring much comfort.”

Mikoto sighed. “No, it’s fine, it’s just frustrating,” she said. “I’m not worried, I don’t care what I’m into, but… I’d just like to know.”

“It is important to know oneself, but you can’t rush these things, either. Time will reveal all.” Kuroko’s voice was soft, embracing Mikoto from afar — but all she received in response was a groan.

“Not satisfied with that answer, are you?” Kuroko continued. “You’re always so impatient. I have a suggestion if you’d like to hear it.”

This had been weighing on Mikoto for quite some time, and she’d found no way to alleviate her stress — so, she perked up at Kuroko’s words, excited by the sliver of hope. “What is it?”

“One way to discover whether you like girls,” Kuroko twirled a finger in the air, “is to kiss one.”

“W-What?” Mikoto’s jaw snapped open. Kuroko spoke like it was the most obvious thing in the world, but it caught Mikoto off-guard, knocking the breath from her lungs. Her face was red with equal parts of anger and embarrassment. “Kuroko, if this is another one of your perverted fantasies, I swear to god—“

Kuroko put up a hand. “Don’t get the wrong idea, Onee-sama, I make this suggestion out of the goodness of my heart. I want to alleviate your frustrations, and, well…” Kuroko gestured to herself. “You have a perfectly willing _and_ beautiful test subject right here.”

Mikoto narrowed her eyes. Despite the smugness oozing from her expression, she couldn’t detect anything sinister behind Kuroko’s words. For once, Mikoto found herself unexpectedly dry of rebuttals, and eventually sighed in defeat. “I can’t believe I’m considering this.” Mikoto shook her head.

Then, slowly she sat up, throwing the covers off her body. She crossed her legs, pointedly avoiding Kuroko’s gaze and patted the spot in front of her.Kuroko happily skipped over, sitting in the designated spot, and Mikoto could only imagine the smug grin on her face.

Mikoto shifted, staring into her lap. “D-Don’t make this weird, okay? The second you do— you promised, remember?”

“I promised.”

“This doesn’t mean anything. So don’t get ahead of yourself, and if I say stop, you’d better stop immediately. And also, I don’t want you to bring this up ever again! Don’t brag to Uiharu-san, or Saten-san, or—“

“Onee-sama.” The firmness of the words, coming down like a gavel, stopped Mikoto in her tracks. “I understand.”

Mikoto finally looked up found Kuroko staring back at her, her eyes swirling with radiance and calmness. That look alone stilled her restless heart, her doubts drifting away like leaves in autumn.

Mikoto’s breath escaped her, and for a moment, she was suspended in awe. Gently, she lowered herself down, finding her footing once more. “Good,” she said. She rubbed the back of her neck. “I, um, I’ve never kissed anyone before…”

“That’s quite alright,” Kuroko said. “Leave it to Kuroko.”

Kuroko had been waiting for this moment all her life. It came to her naturally, for she had rehearsed many times before — slowly, she leaned in, and her eyes fluttered closed. Mikoto watched as the space between them began to shrink, and found herself unusually stiff as if her joints were rusted. She was sweating, she was shaking, but she leaned to meet Kuroko halfway.

It was the gentlest touch. Like a soft breath, or a breeze skimming across a lake. Kuroko’s lips met her own and they lingered there, as this strange sensation began to unravel itself. A wave of goosebumps came and went, leaving warmth and vitality in their wake. Mikoto had never felt anything like it.

She hadn’t noticed how long Kuroko’s eyelashes were until she could feel them brushing against her cheek, or how nice Kuroko’s perfume smelt until it was all she could breathe in. She wondered how much of Kuroko she had overlooked until now and hoped it wasn’t plenty — because the pieces she found were beautiful.

It was a fleeting moment. Before Mikoto could grab hold of it all, it slipped from her grasp. They pulled away and everything stopped. They gazed at each other as if for the first time, both enthralled and silent.

They sat like that for a while. Kuroko’s expression had become somewhat more timid as she struggled to keep up with her roaring heartbeat. “Well?” she said, looking at Mikoto expectantly.

“I… I don’t know,” Mikoto said. Everything was over too quickly — she had been showered in plenty and stripped of it in an instant. The only thing that remained was this strange magnetism, pulling them closer.

Mikoto was strangely calm as she lifted a hand to Kuroko’s cheek. Kuroko’s eyes went wide at the unexpected touch, and guided by the gentle tug, she leaned in and placed another kiss to Mikoto’s lips.

This time, Mikoto made sure to savour every inch of it. They took it slow. Their lips softly parted, taking breaths in time with one another. As their confidence grew they leaned in closer, pushed a little harder, gave a little more. Mikoto let out a hum of relaxation, her body enveloped in this blooming warmth. “Mm…”

Kuroko’s heart leapt at the sound. She could feel Mikoto’s voice buzzing against her lips, a sign it wasn’t just her imagination, but it felt too dreamy — her senses were clouded and hazy. Mikoto’s lip balm tasted too sweet, the hand on her cheek caressed her too gently to be real. It was too good to be true.

And yet, the moment went on. They kissed again and again. Kuroko’s face had never felt so hot, she surely thought she would faint — but she never once tried to pull away, a flush of adrenaline filling her whenever Mikoto eagerly kissed her back.

Kuroko’s hand searched the bedsheets until she brushed Mikoto’s fingertips. She interlaced their fingers together, giving her a tight squeeze, and again, Mikoto squeezed back.

Every show of affection Kuroko gave, Mikoto returned. She wasn’t used to that.

And before she could even think about pushing her luck, Mikoto pulled away. Kuroko wanted to scream, to grab her by the collar and kiss her again, to pin her to the bed and claim her for good — this might be her only chance, after all.

But her heartbeat throbbed in her ears a little too loudly. Her thoughts were too far away, floating in her daze, and all she could do was stare at Mikoto. Mikoto was red-faced too, and there was something about the look in her eye — she had never looked at Kuroko like that before. Kuroko dared to call it romantic.

But she didn’t say anything. Her lips tingled, and under Mikoto’s firm gaze, Kuroko felt a little timid. Mikoto was the one to break the silence, eventually glancing away. “Thanks, Kuroko.”

“You’re welcome…” Kuroko blinked, looking like a deer in headlights. She’d loved Mikoto for a long time, but had never felt this flustered. “Did you… come up with an answer?”

“Yeah,” Mikoto said. “I’m going to sleep now.”

Kuroko felt a pang of disappointment. “You’re not going to tell me what it is?”

“I don’t have to.”

“You can’t leave me in the dark.”

“Watch me.”

“Onee-sama!” Kuroko finally came to her senses — she lunged forward, beating her fists against Mikoto’s chest. “That’s so cruel! How could you do that, after Kuroko went so far to help you?”

The display was nothing but adorable, and Mikoto laughed instead of trying to fight back. “I know, I’m sorry.” She put a hand on Kuroko’s head. “As soon as I’m ready to talk about this again, I’ll let you know. I promise.”

_I promise._

Kuroko looked up at Mikoto, saw the smile on her lips, and sighed. She couldn’t argue with that.

So they shared goodnights, turned off the lights, and went to bed. Kuroko let out a long, shaky breath — she hadn’t realised how tense she had been until then. Her muscles relaxed and her eyes closed, but she knew she wasn’t getting any sleep after that.

She’d kissed Mikoto. How surreal.

In the days that passed, Kuroko noticed their relationship had changed somewhat. Mikoto treated her with a touch more tenderness and affection; as if she had grown more attached to it, Mikoto called her name more often. She craved physical contact, and frequently reached out for friendly touches; putting a hand on Kuroko’s shoulder, giving a quick squeeze on the arm, and such.

And Kuroko, in response, was quieter and more content. Her fits of perversion lessened and were replaced with occasional timidness; eyes that used to stare at Mikoto unabashedly now hesitated, before glancing away. When Kuroko needed it most, her confidence was nowhere to be found. She tried to ask Mikoto why things had changed, why she was being kinder, why she looked at her like _that_ all the time, but nothing ever came out.

Could it be? No, Kuroko shook her head. There was no way Mikoto loved her back.

Right?

Kuroko had many sleepless nights after that. _Onee-sama promised,_ she remembered. _She promised to tell me how she felt._ And that gave her hope.

Because Mikoto never broke her promises.


End file.
